Some notable changes, from upstream's release notes: - sshd(8): Remove support for obsolete "host/port" syntax. - ssh(1): When prompting whether to record a new host key, accept the key fingerprint as a synonym for "yes". - ssh-keygen(1): when acting as a CA and signing certificates with an RSA key, default to using the rsa-sha2-512 signature algorithm. - ssh(1), sshd(8), ssh-keygen(1): this release removes the "ssh-rsa" (RSA/SHA1) algorithm from those accepted for certificate signatures. - ssh-sk-helper(8): this is a new binary. It is used by the FIDO/U2F support to provide address-space isolation for token middleware libraries (including the internal one). - ssh(1): this release enables UpdateHostkeys by default subject to some conservative preconditions. - scp(1): this release changes the behaviour of remote to remote copies (e.g. "scp host-a:/path host-b:") to transfer through the local host by default. - scp(1): experimental support for transfers using the SFTP protocol as a replacement for the venerable SCP/RCP protocol that it has traditionally used. Additional integration work is needed to support FIDO/U2F in the base system. Deprecation Notice ------------------ OpenSSH will disable the ssh-rsa signature scheme by default in the next release. Reviewed by: imp MFC after: 1 month Relnotes: Yes Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D29985
1066 lines
29 KiB
C
1066 lines
29 KiB
C
/* $OpenBSD: auth.c,v 1.153 2021/07/05 00:50:25 dtucker Exp $ */
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/*
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* Copyright (c) 2000 Markus Friedl. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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__RCSID("$FreeBSD$");
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/socket.h>
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#include <sys/wait.h>
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#include <netinet/in.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <fcntl.h>
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#ifdef HAVE_PATHS_H
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# include <paths.h>
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#endif
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#include <pwd.h>
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#ifdef HAVE_LOGIN_H
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#include <login.h>
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#endif
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#ifdef USE_SHADOW
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#include <shadow.h>
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#endif
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#include <stdarg.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <limits.h>
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#include <netdb.h>
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#include <time.h>
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#include "xmalloc.h"
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#include "match.h"
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#include "groupaccess.h"
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#include "log.h"
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#include "sshbuf.h"
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#include "misc.h"
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#include "servconf.h"
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#include "sshkey.h"
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#include "hostfile.h"
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#include "auth.h"
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#include "auth-options.h"
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#include "canohost.h"
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#include "uidswap.h"
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#include "packet.h"
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#include "loginrec.h"
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#ifdef GSSAPI
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#include "ssh-gss.h"
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#endif
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#include "authfile.h"
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#include "monitor_wrap.h"
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#include "ssherr.h"
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#include "compat.h"
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#include "channels.h"
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#include "blacklist_client.h"
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/* import */
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extern ServerOptions options;
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extern struct include_list includes;
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extern int use_privsep;
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extern struct sshbuf *loginmsg;
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extern struct passwd *privsep_pw;
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extern struct sshauthopt *auth_opts;
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/* Debugging messages */
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static struct sshbuf *auth_debug;
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/*
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* Check if the user is allowed to log in via ssh. If user is listed
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* in DenyUsers or one of user's groups is listed in DenyGroups, false
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* will be returned. If AllowUsers isn't empty and user isn't listed
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* there, or if AllowGroups isn't empty and one of user's groups isn't
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* listed there, false will be returned.
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* If the user's shell is not executable, false will be returned.
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* Otherwise true is returned.
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*/
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int
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allowed_user(struct ssh *ssh, struct passwd * pw)
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{
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struct stat st;
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const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
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u_int i;
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int r;
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#ifdef USE_SHADOW
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struct spwd *spw = NULL;
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#endif
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/* Shouldn't be called if pw is NULL, but better safe than sorry... */
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if (!pw || !pw->pw_name)
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return 0;
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#ifdef USE_SHADOW
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if (!options.use_pam)
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spw = getspnam(pw->pw_name);
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#ifdef HAS_SHADOW_EXPIRE
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if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
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return 0;
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#endif /* HAS_SHADOW_EXPIRE */
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#endif /* USE_SHADOW */
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/* grab passwd field for locked account check */
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passwd = pw->pw_passwd;
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#ifdef USE_SHADOW
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if (spw != NULL)
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#ifdef USE_LIBIAF
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passwd = get_iaf_password(pw);
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#else
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passwd = spw->sp_pwdp;
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#endif /* USE_LIBIAF */
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#endif
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/* check for locked account */
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if (!options.use_pam && passwd && *passwd) {
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int locked = 0;
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#ifdef LOCKED_PASSWD_STRING
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if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
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locked = 1;
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#endif
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#ifdef LOCKED_PASSWD_PREFIX
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if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
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strlen(LOCKED_PASSWD_PREFIX)) == 0)
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locked = 1;
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#endif
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#ifdef LOCKED_PASSWD_SUBSTR
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if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
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locked = 1;
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#endif
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#ifdef USE_LIBIAF
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free((void *) passwd);
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#endif /* USE_LIBIAF */
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if (locked) {
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logit("User %.100s not allowed because account is locked",
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pw->pw_name);
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return 0;
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}
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}
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/*
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* Deny if shell does not exist or is not executable unless we
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* are chrooting.
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*/
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if (options.chroot_directory == NULL ||
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strcasecmp(options.chroot_directory, "none") == 0) {
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char *shell = xstrdup((pw->pw_shell[0] == '\0') ?
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_PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */
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if (stat(shell, &st) == -1) {
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logit("User %.100s not allowed because shell %.100s "
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"does not exist", pw->pw_name, shell);
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free(shell);
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return 0;
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}
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if (S_ISREG(st.st_mode) == 0 ||
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(st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
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logit("User %.100s not allowed because shell %.100s "
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"is not executable", pw->pw_name, shell);
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free(shell);
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return 0;
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}
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free(shell);
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}
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if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
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options.num_deny_groups > 0 || options.num_allow_groups > 0) {
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hostname = auth_get_canonical_hostname(ssh, options.use_dns);
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ipaddr = ssh_remote_ipaddr(ssh);
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}
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/* Return false if user is listed in DenyUsers */
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if (options.num_deny_users > 0) {
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for (i = 0; i < options.num_deny_users; i++) {
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r = match_user(pw->pw_name, hostname, ipaddr,
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options.deny_users[i]);
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if (r < 0) {
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fatal("Invalid DenyUsers pattern \"%.100s\"",
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options.deny_users[i]);
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} else if (r != 0) {
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logit("User %.100s from %.100s not allowed "
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"because listed in DenyUsers",
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pw->pw_name, hostname);
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return 0;
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}
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}
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}
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/* Return false if AllowUsers isn't empty and user isn't listed there */
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if (options.num_allow_users > 0) {
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for (i = 0; i < options.num_allow_users; i++) {
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r = match_user(pw->pw_name, hostname, ipaddr,
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options.allow_users[i]);
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if (r < 0) {
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fatal("Invalid AllowUsers pattern \"%.100s\"",
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options.allow_users[i]);
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} else if (r == 1)
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break;
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}
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/* i < options.num_allow_users iff we break for loop */
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if (i >= options.num_allow_users) {
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logit("User %.100s from %.100s not allowed because "
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"not listed in AllowUsers", pw->pw_name, hostname);
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return 0;
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}
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}
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if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
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/* Get the user's group access list (primary and supplementary) */
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if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
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logit("User %.100s from %.100s not allowed because "
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"not in any group", pw->pw_name, hostname);
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return 0;
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}
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/* Return false if one of user's groups is listed in DenyGroups */
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if (options.num_deny_groups > 0)
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if (ga_match(options.deny_groups,
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options.num_deny_groups)) {
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ga_free();
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logit("User %.100s from %.100s not allowed "
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"because a group is listed in DenyGroups",
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pw->pw_name, hostname);
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return 0;
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}
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/*
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* Return false if AllowGroups isn't empty and one of user's groups
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* isn't listed there
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*/
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if (options.num_allow_groups > 0)
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if (!ga_match(options.allow_groups,
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options.num_allow_groups)) {
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ga_free();
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logit("User %.100s from %.100s not allowed "
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"because none of user's groups are listed "
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"in AllowGroups", pw->pw_name, hostname);
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return 0;
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}
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ga_free();
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}
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#ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
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if (!sys_auth_allowed_user(pw, loginmsg))
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return 0;
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#endif
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/* We found no reason not to let this user try to log on... */
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return 1;
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}
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/*
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* Formats any key left in authctxt->auth_method_key for inclusion in
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* auth_log()'s message. Also includes authxtct->auth_method_info if present.
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*/
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static char *
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format_method_key(Authctxt *authctxt)
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{
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const struct sshkey *key = authctxt->auth_method_key;
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const char *methinfo = authctxt->auth_method_info;
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char *fp, *cafp, *ret = NULL;
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if (key == NULL)
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return NULL;
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if (sshkey_is_cert(key)) {
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fp = sshkey_fingerprint(key,
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options.fingerprint_hash, SSH_FP_DEFAULT);
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cafp = sshkey_fingerprint(key->cert->signature_key,
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options.fingerprint_hash, SSH_FP_DEFAULT);
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xasprintf(&ret, "%s %s ID %s (serial %llu) CA %s %s%s%s",
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sshkey_type(key), fp == NULL ? "(null)" : fp,
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key->cert->key_id,
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(unsigned long long)key->cert->serial,
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sshkey_type(key->cert->signature_key),
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cafp == NULL ? "(null)" : cafp,
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methinfo == NULL ? "" : ", ",
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methinfo == NULL ? "" : methinfo);
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free(fp);
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free(cafp);
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} else {
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fp = sshkey_fingerprint(key, options.fingerprint_hash,
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SSH_FP_DEFAULT);
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xasprintf(&ret, "%s %s%s%s", sshkey_type(key),
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fp == NULL ? "(null)" : fp,
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methinfo == NULL ? "" : ", ",
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methinfo == NULL ? "" : methinfo);
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free(fp);
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}
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return ret;
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}
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void
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auth_log(struct ssh *ssh, int authenticated, int partial,
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const char *method, const char *submethod)
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{
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Authctxt *authctxt = (Authctxt *)ssh->authctxt;
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int level = SYSLOG_LEVEL_VERBOSE;
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const char *authmsg;
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char *extra = NULL;
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if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
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return;
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/* Raise logging level */
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if (authenticated == 1 ||
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!authctxt->valid ||
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authctxt->failures >= options.max_authtries / 2 ||
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strcmp(method, "password") == 0)
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level = SYSLOG_LEVEL_INFO;
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if (authctxt->postponed)
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authmsg = "Postponed";
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else if (partial)
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authmsg = "Partial";
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else {
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authmsg = authenticated ? "Accepted" : "Failed";
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if (authenticated)
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BLACKLIST_NOTIFY(BLACKLIST_AUTH_OK, "ssh");
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}
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if ((extra = format_method_key(authctxt)) == NULL) {
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if (authctxt->auth_method_info != NULL)
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extra = xstrdup(authctxt->auth_method_info);
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}
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do_log2(level, "%s %s%s%s for %s%.100s from %.200s port %d ssh2%s%s",
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authmsg,
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method,
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submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod,
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authctxt->valid ? "" : "invalid user ",
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authctxt->user,
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ssh_remote_ipaddr(ssh),
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ssh_remote_port(ssh),
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extra != NULL ? ": " : "",
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extra != NULL ? extra : "");
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free(extra);
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#if defined(CUSTOM_FAILED_LOGIN) || defined(SSH_AUDIT_EVENTS)
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if (authenticated == 0 && !(authctxt->postponed || partial)) {
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/* Log failed login attempt */
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# ifdef CUSTOM_FAILED_LOGIN
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if (strcmp(method, "password") == 0 ||
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strncmp(method, "keyboard-interactive", 20) == 0 ||
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strcmp(method, "challenge-response") == 0)
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record_failed_login(ssh, authctxt->user,
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auth_get_canonical_hostname(ssh, options.use_dns), "ssh");
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# endif
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# ifdef SSH_AUDIT_EVENTS
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audit_event(ssh, audit_classify_auth(method));
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# endif
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}
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#endif
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#if defined(CUSTOM_FAILED_LOGIN) && defined(WITH_AIXAUTHENTICATE)
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if (authenticated)
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sys_auth_record_login(authctxt->user,
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auth_get_canonical_hostname(ssh, options.use_dns), "ssh",
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loginmsg);
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#endif
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}
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void
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auth_maxtries_exceeded(struct ssh *ssh)
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{
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Authctxt *authctxt = (Authctxt *)ssh->authctxt;
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error("maximum authentication attempts exceeded for "
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"%s%.100s from %.200s port %d ssh2",
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authctxt->valid ? "" : "invalid user ",
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authctxt->user,
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ssh_remote_ipaddr(ssh),
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ssh_remote_port(ssh));
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ssh_packet_disconnect(ssh, "Too many authentication failures");
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/* NOTREACHED */
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}
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|
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/*
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* Check whether root logins are disallowed.
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*/
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int
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auth_root_allowed(struct ssh *ssh, const char *method)
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{
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switch (options.permit_root_login) {
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case PERMIT_YES:
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return 1;
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case PERMIT_NO_PASSWD:
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if (strcmp(method, "publickey") == 0 ||
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strcmp(method, "hostbased") == 0 ||
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strcmp(method, "gssapi-with-mic") == 0)
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return 1;
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break;
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case PERMIT_FORCED_ONLY:
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if (auth_opts->force_command != NULL) {
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logit("Root login accepted for forced command.");
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return 1;
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}
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break;
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}
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logit("ROOT LOGIN REFUSED FROM %.200s port %d",
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ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
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return 0;
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}
|
|
|
|
|
|
/*
|
|
* Given a template and a passwd structure, build a filename
|
|
* by substituting % tokenised options. Currently, %% becomes '%',
|
|
* %h becomes the home directory and %u the username.
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|
*
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* This returns a buffer allocated by xmalloc.
|
|
*/
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char *
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expand_authorized_keys(const char *filename, struct passwd *pw)
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|
{
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char *file, uidstr[32], ret[PATH_MAX];
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int i;
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|
|
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snprintf(uidstr, sizeof(uidstr), "%llu",
|
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(unsigned long long)pw->pw_uid);
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file = percent_expand(filename, "h", pw->pw_dir,
|
|
"u", pw->pw_name, "U", uidstr, (char *)NULL);
|
|
|
|
/*
|
|
* Ensure that filename starts anchored. If not, be backward
|
|
* compatible and prepend the '%h/'
|
|
*/
|
|
if (path_absolute(file))
|
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return (file);
|
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|
|
i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
|
|
if (i < 0 || (size_t)i >= sizeof(ret))
|
|
fatal("expand_authorized_keys: path too long");
|
|
free(file);
|
|
return (xstrdup(ret));
|
|
}
|
|
|
|
char *
|
|
authorized_principals_file(struct passwd *pw)
|
|
{
|
|
if (options.authorized_principals_file == NULL)
|
|
return NULL;
|
|
return expand_authorized_keys(options.authorized_principals_file, pw);
|
|
}
|
|
|
|
/* return ok if key exists in sysfile or userfile */
|
|
HostStatus
|
|
check_key_in_hostfiles(struct passwd *pw, struct sshkey *key, const char *host,
|
|
const char *sysfile, const char *userfile)
|
|
{
|
|
char *user_hostfile;
|
|
struct stat st;
|
|
HostStatus host_status;
|
|
struct hostkeys *hostkeys;
|
|
const struct hostkey_entry *found;
|
|
|
|
hostkeys = init_hostkeys();
|
|
load_hostkeys(hostkeys, host, sysfile, 0);
|
|
if (userfile != NULL) {
|
|
user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
|
|
if (options.strict_modes &&
|
|
(stat(user_hostfile, &st) == 0) &&
|
|
((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
|
|
(st.st_mode & 022) != 0)) {
|
|
logit("Authentication refused for %.100s: "
|
|
"bad owner or modes for %.200s",
|
|
pw->pw_name, user_hostfile);
|
|
auth_debug_add("Ignored %.200s: bad ownership or modes",
|
|
user_hostfile);
|
|
} else {
|
|
temporarily_use_uid(pw);
|
|
load_hostkeys(hostkeys, host, user_hostfile, 0);
|
|
restore_uid();
|
|
}
|
|
free(user_hostfile);
|
|
}
|
|
host_status = check_key_in_hostkeys(hostkeys, key, &found);
|
|
if (host_status == HOST_REVOKED)
|
|
error("WARNING: revoked key for %s attempted authentication",
|
|
host);
|
|
else if (host_status == HOST_OK)
|
|
debug_f("key for %s found at %s:%ld",
|
|
found->host, found->file, found->line);
|
|
else
|
|
debug_f("key for host %s not found", host);
|
|
|
|
free_hostkeys(hostkeys);
|
|
|
|
return host_status;
|
|
}
|
|
|
|
static FILE *
|
|
auth_openfile(const char *file, struct passwd *pw, int strict_modes,
|
|
int log_missing, char *file_type)
|
|
{
|
|
char line[1024];
|
|
struct stat st;
|
|
int fd;
|
|
FILE *f;
|
|
|
|
if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) {
|
|
if (log_missing || errno != ENOENT)
|
|
debug("Could not open %s '%s': %s", file_type, file,
|
|
strerror(errno));
|
|
return NULL;
|
|
}
|
|
|
|
if (fstat(fd, &st) == -1) {
|
|
close(fd);
|
|
return NULL;
|
|
}
|
|
if (!S_ISREG(st.st_mode)) {
|
|
logit("User %s %s %s is not a regular file",
|
|
pw->pw_name, file_type, file);
|
|
close(fd);
|
|
return NULL;
|
|
}
|
|
unset_nonblock(fd);
|
|
if ((f = fdopen(fd, "r")) == NULL) {
|
|
close(fd);
|
|
return NULL;
|
|
}
|
|
if (strict_modes &&
|
|
safe_path_fd(fileno(f), file, pw, line, sizeof(line)) != 0) {
|
|
fclose(f);
|
|
logit("Authentication refused: %s", line);
|
|
auth_debug_add("Ignored %s: %s", file_type, line);
|
|
return NULL;
|
|
}
|
|
|
|
return f;
|
|
}
|
|
|
|
|
|
FILE *
|
|
auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes)
|
|
{
|
|
return auth_openfile(file, pw, strict_modes, 1, "authorized keys");
|
|
}
|
|
|
|
FILE *
|
|
auth_openprincipals(const char *file, struct passwd *pw, int strict_modes)
|
|
{
|
|
return auth_openfile(file, pw, strict_modes, 0,
|
|
"authorized principals");
|
|
}
|
|
|
|
struct passwd *
|
|
getpwnamallow(struct ssh *ssh, const char *user)
|
|
{
|
|
#ifdef HAVE_LOGIN_CAP
|
|
extern login_cap_t *lc;
|
|
#ifdef HAVE_AUTH_HOSTOK
|
|
const char *from_host, *from_ip;
|
|
#endif
|
|
#ifdef BSD_AUTH
|
|
auth_session_t *as;
|
|
#endif
|
|
#endif
|
|
struct passwd *pw;
|
|
struct connection_info *ci;
|
|
u_int i;
|
|
|
|
ci = get_connection_info(ssh, 1, options.use_dns);
|
|
ci->user = user;
|
|
parse_server_match_config(&options, &includes, ci);
|
|
log_change_level(options.log_level);
|
|
log_verbose_reset();
|
|
for (i = 0; i < options.num_log_verbose; i++)
|
|
log_verbose_add(options.log_verbose[i]);
|
|
process_permitopen(ssh, &options);
|
|
|
|
#if defined(_AIX) && defined(HAVE_SETAUTHDB)
|
|
aix_setauthdb(user);
|
|
#endif
|
|
|
|
pw = getpwnam(user);
|
|
|
|
#if defined(_AIX) && defined(HAVE_SETAUTHDB)
|
|
aix_restoreauthdb();
|
|
#endif
|
|
if (pw == NULL) {
|
|
BLACKLIST_NOTIFY(BLACKLIST_BAD_USER, user);
|
|
logit("Invalid user %.100s from %.100s port %d",
|
|
user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
|
|
#ifdef CUSTOM_FAILED_LOGIN
|
|
record_failed_login(ssh, user,
|
|
auth_get_canonical_hostname(ssh, options.use_dns), "ssh");
|
|
#endif
|
|
#ifdef SSH_AUDIT_EVENTS
|
|
audit_event(ssh, SSH_INVALID_USER);
|
|
#endif /* SSH_AUDIT_EVENTS */
|
|
return (NULL);
|
|
}
|
|
if (!allowed_user(ssh, pw))
|
|
return (NULL);
|
|
#ifdef HAVE_LOGIN_CAP
|
|
if ((lc = login_getpwclass(pw)) == NULL) {
|
|
debug("unable to get login class: %s", user);
|
|
return (NULL);
|
|
}
|
|
#ifdef HAVE_AUTH_HOSTOK
|
|
from_host = auth_get_canonical_hostname(ssh, options.use_dns);
|
|
from_ip = ssh_remote_ipaddr(ssh);
|
|
if (!auth_hostok(lc, from_host, from_ip)) {
|
|
debug("Denied connection for %.200s from %.200s [%.200s].",
|
|
pw->pw_name, from_host, from_ip);
|
|
return (NULL);
|
|
}
|
|
#endif /* HAVE_AUTH_HOSTOK */
|
|
#ifdef HAVE_AUTH_TIMEOK
|
|
if (!auth_timeok(lc, time(NULL))) {
|
|
debug("LOGIN %.200s REFUSED (TIME)", pw->pw_name);
|
|
return (NULL);
|
|
}
|
|
#endif /* HAVE_AUTH_TIMEOK */
|
|
#ifdef BSD_AUTH
|
|
if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
|
|
auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
|
|
debug("Approval failure for %s", user);
|
|
pw = NULL;
|
|
}
|
|
if (as != NULL)
|
|
auth_close(as);
|
|
#endif
|
|
#endif
|
|
if (pw != NULL)
|
|
return (pwcopy(pw));
|
|
return (NULL);
|
|
}
|
|
|
|
/* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */
|
|
int
|
|
auth_key_is_revoked(struct sshkey *key)
|
|
{
|
|
char *fp = NULL;
|
|
int r;
|
|
|
|
if (options.revoked_keys_file == NULL)
|
|
return 0;
|
|
if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
|
|
SSH_FP_DEFAULT)) == NULL) {
|
|
r = SSH_ERR_ALLOC_FAIL;
|
|
error_fr(r, "fingerprint key");
|
|
goto out;
|
|
}
|
|
|
|
r = sshkey_check_revoked(key, options.revoked_keys_file);
|
|
switch (r) {
|
|
case 0:
|
|
break; /* not revoked */
|
|
case SSH_ERR_KEY_REVOKED:
|
|
error("Authentication key %s %s revoked by file %s",
|
|
sshkey_type(key), fp, options.revoked_keys_file);
|
|
goto out;
|
|
default:
|
|
error_r(r, "Error checking authentication key %s %s in "
|
|
"revoked keys file %s", sshkey_type(key), fp,
|
|
options.revoked_keys_file);
|
|
goto out;
|
|
}
|
|
|
|
/* Success */
|
|
r = 0;
|
|
|
|
out:
|
|
free(fp);
|
|
return r == 0 ? 0 : 1;
|
|
}
|
|
|
|
void
|
|
auth_debug_add(const char *fmt,...)
|
|
{
|
|
char buf[1024];
|
|
va_list args;
|
|
int r;
|
|
|
|
if (auth_debug == NULL)
|
|
return;
|
|
|
|
va_start(args, fmt);
|
|
vsnprintf(buf, sizeof(buf), fmt, args);
|
|
va_end(args);
|
|
if ((r = sshbuf_put_cstring(auth_debug, buf)) != 0)
|
|
fatal_fr(r, "sshbuf_put_cstring");
|
|
}
|
|
|
|
void
|
|
auth_debug_send(struct ssh *ssh)
|
|
{
|
|
char *msg;
|
|
int r;
|
|
|
|
if (auth_debug == NULL)
|
|
return;
|
|
while (sshbuf_len(auth_debug) != 0) {
|
|
if ((r = sshbuf_get_cstring(auth_debug, &msg, NULL)) != 0)
|
|
fatal_fr(r, "sshbuf_get_cstring");
|
|
ssh_packet_send_debug(ssh, "%s", msg);
|
|
free(msg);
|
|
}
|
|
}
|
|
|
|
void
|
|
auth_debug_reset(void)
|
|
{
|
|
if (auth_debug != NULL)
|
|
sshbuf_reset(auth_debug);
|
|
else if ((auth_debug = sshbuf_new()) == NULL)
|
|
fatal_f("sshbuf_new failed");
|
|
}
|
|
|
|
struct passwd *
|
|
fakepw(void)
|
|
{
|
|
static struct passwd fake;
|
|
|
|
memset(&fake, 0, sizeof(fake));
|
|
fake.pw_name = "NOUSER";
|
|
fake.pw_passwd =
|
|
"$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
|
|
#ifdef HAVE_STRUCT_PASSWD_PW_GECOS
|
|
fake.pw_gecos = "NOUSER";
|
|
#endif
|
|
fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
|
|
fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
|
|
#ifdef HAVE_STRUCT_PASSWD_PW_CLASS
|
|
fake.pw_class = "";
|
|
#endif
|
|
fake.pw_dir = "/nonexist";
|
|
fake.pw_shell = "/nonexist";
|
|
|
|
return (&fake);
|
|
}
|
|
|
|
/*
|
|
* Returns the remote DNS hostname as a string. The returned string must not
|
|
* be freed. NB. this will usually trigger a DNS query the first time it is
|
|
* called.
|
|
* This function does additional checks on the hostname to mitigate some
|
|
* attacks on based on conflation of hostnames and IP addresses.
|
|
*/
|
|
|
|
static char *
|
|
remote_hostname(struct ssh *ssh)
|
|
{
|
|
struct sockaddr_storage from;
|
|
socklen_t fromlen;
|
|
struct addrinfo hints, *ai, *aitop;
|
|
char name[NI_MAXHOST], ntop2[NI_MAXHOST];
|
|
const char *ntop = ssh_remote_ipaddr(ssh);
|
|
|
|
/* Get IP address of client. */
|
|
fromlen = sizeof(from);
|
|
memset(&from, 0, sizeof(from));
|
|
if (getpeername(ssh_packet_get_connection_in(ssh),
|
|
(struct sockaddr *)&from, &fromlen) == -1) {
|
|
debug("getpeername failed: %.100s", strerror(errno));
|
|
return xstrdup(ntop);
|
|
}
|
|
|
|
ipv64_normalise_mapped(&from, &fromlen);
|
|
if (from.ss_family == AF_INET6)
|
|
fromlen = sizeof(struct sockaddr_in6);
|
|
|
|
debug3("Trying to reverse map address %.100s.", ntop);
|
|
/* Map the IP address to a host name. */
|
|
if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
|
|
NULL, 0, NI_NAMEREQD) != 0) {
|
|
/* Host name not found. Use ip address. */
|
|
return xstrdup(ntop);
|
|
}
|
|
|
|
/*
|
|
* if reverse lookup result looks like a numeric hostname,
|
|
* someone is trying to trick us by PTR record like following:
|
|
* 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5
|
|
*/
|
|
memset(&hints, 0, sizeof(hints));
|
|
hints.ai_socktype = SOCK_DGRAM; /*dummy*/
|
|
hints.ai_flags = AI_NUMERICHOST;
|
|
if (getaddrinfo(name, NULL, &hints, &ai) == 0) {
|
|
logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
|
|
name, ntop);
|
|
freeaddrinfo(ai);
|
|
return xstrdup(ntop);
|
|
}
|
|
|
|
/* Names are stored in lowercase. */
|
|
lowercase(name);
|
|
|
|
/*
|
|
* Map it back to an IP address and check that the given
|
|
* address actually is an address of this host. This is
|
|
* necessary because anyone with access to a name server can
|
|
* define arbitrary names for an IP address. Mapping from
|
|
* name to IP address can be trusted better (but can still be
|
|
* fooled if the intruder has access to the name server of
|
|
* the domain).
|
|
*/
|
|
memset(&hints, 0, sizeof(hints));
|
|
hints.ai_family = from.ss_family;
|
|
hints.ai_socktype = SOCK_STREAM;
|
|
if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
|
|
logit("reverse mapping checking getaddrinfo for %.700s "
|
|
"[%s] failed.", name, ntop);
|
|
return xstrdup(ntop);
|
|
}
|
|
/* Look for the address from the list of addresses. */
|
|
for (ai = aitop; ai; ai = ai->ai_next) {
|
|
if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
|
|
sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
|
|
(strcmp(ntop, ntop2) == 0))
|
|
break;
|
|
}
|
|
freeaddrinfo(aitop);
|
|
/* If we reached the end of the list, the address was not there. */
|
|
if (ai == NULL) {
|
|
/* Address not found for the host name. */
|
|
logit("Address %.100s maps to %.600s, but this does not "
|
|
"map back to the address.", ntop, name);
|
|
return xstrdup(ntop);
|
|
}
|
|
return xstrdup(name);
|
|
}
|
|
|
|
/*
|
|
* Return the canonical name of the host in the other side of the current
|
|
* connection. The host name is cached, so it is efficient to call this
|
|
* several times.
|
|
*/
|
|
|
|
const char *
|
|
auth_get_canonical_hostname(struct ssh *ssh, int use_dns)
|
|
{
|
|
static char *dnsname;
|
|
|
|
if (!use_dns)
|
|
return ssh_remote_ipaddr(ssh);
|
|
else if (dnsname != NULL)
|
|
return dnsname;
|
|
else {
|
|
dnsname = remote_hostname(ssh);
|
|
return dnsname;
|
|
}
|
|
}
|
|
|
|
/* These functions link key/cert options to the auth framework */
|
|
|
|
/* Log sshauthopt options locally and (optionally) for remote transmission */
|
|
void
|
|
auth_log_authopts(const char *loc, const struct sshauthopt *opts, int do_remote)
|
|
{
|
|
int do_env = options.permit_user_env && opts->nenv > 0;
|
|
int do_permitopen = opts->npermitopen > 0 &&
|
|
(options.allow_tcp_forwarding & FORWARD_LOCAL) != 0;
|
|
int do_permitlisten = opts->npermitlisten > 0 &&
|
|
(options.allow_tcp_forwarding & FORWARD_REMOTE) != 0;
|
|
size_t i;
|
|
char msg[1024], buf[64];
|
|
|
|
snprintf(buf, sizeof(buf), "%d", opts->force_tun_device);
|
|
/* Try to keep this alphabetically sorted */
|
|
snprintf(msg, sizeof(msg), "key options:%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
|
|
opts->permit_agent_forwarding_flag ? " agent-forwarding" : "",
|
|
opts->force_command == NULL ? "" : " command",
|
|
do_env ? " environment" : "",
|
|
opts->valid_before == 0 ? "" : "expires",
|
|
opts->no_require_user_presence ? " no-touch-required" : "",
|
|
do_permitopen ? " permitopen" : "",
|
|
do_permitlisten ? " permitlisten" : "",
|
|
opts->permit_port_forwarding_flag ? " port-forwarding" : "",
|
|
opts->cert_principals == NULL ? "" : " principals",
|
|
opts->permit_pty_flag ? " pty" : "",
|
|
opts->require_verify ? " uv" : "",
|
|
opts->force_tun_device == -1 ? "" : " tun=",
|
|
opts->force_tun_device == -1 ? "" : buf,
|
|
opts->permit_user_rc ? " user-rc" : "",
|
|
opts->permit_x11_forwarding_flag ? " x11-forwarding" : "");
|
|
|
|
debug("%s: %s", loc, msg);
|
|
if (do_remote)
|
|
auth_debug_add("%s: %s", loc, msg);
|
|
|
|
if (options.permit_user_env) {
|
|
for (i = 0; i < opts->nenv; i++) {
|
|
debug("%s: environment: %s", loc, opts->env[i]);
|
|
if (do_remote) {
|
|
auth_debug_add("%s: environment: %s",
|
|
loc, opts->env[i]);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Go into a little more details for the local logs. */
|
|
if (opts->valid_before != 0) {
|
|
format_absolute_time(opts->valid_before, buf, sizeof(buf));
|
|
debug("%s: expires at %s", loc, buf);
|
|
}
|
|
if (opts->cert_principals != NULL) {
|
|
debug("%s: authorized principals: \"%s\"",
|
|
loc, opts->cert_principals);
|
|
}
|
|
if (opts->force_command != NULL)
|
|
debug("%s: forced command: \"%s\"", loc, opts->force_command);
|
|
if (do_permitopen) {
|
|
for (i = 0; i < opts->npermitopen; i++) {
|
|
debug("%s: permitted open: %s",
|
|
loc, opts->permitopen[i]);
|
|
}
|
|
}
|
|
if (do_permitlisten) {
|
|
for (i = 0; i < opts->npermitlisten; i++) {
|
|
debug("%s: permitted listen: %s",
|
|
loc, opts->permitlisten[i]);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Activate a new set of key/cert options; merging with what is there. */
|
|
int
|
|
auth_activate_options(struct ssh *ssh, struct sshauthopt *opts)
|
|
{
|
|
struct sshauthopt *old = auth_opts;
|
|
const char *emsg = NULL;
|
|
|
|
debug_f("setting new authentication options");
|
|
if ((auth_opts = sshauthopt_merge(old, opts, &emsg)) == NULL) {
|
|
error("Inconsistent authentication options: %s", emsg);
|
|
return -1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* Disable forwarding, etc for the session */
|
|
void
|
|
auth_restrict_session(struct ssh *ssh)
|
|
{
|
|
struct sshauthopt *restricted;
|
|
|
|
debug_f("restricting session");
|
|
|
|
/* A blank sshauthopt defaults to permitting nothing */
|
|
restricted = sshauthopt_new();
|
|
restricted->permit_pty_flag = 1;
|
|
restricted->restricted = 1;
|
|
|
|
if (auth_activate_options(ssh, restricted) != 0)
|
|
fatal_f("failed to restrict session");
|
|
sshauthopt_free(restricted);
|
|
}
|
|
|
|
int
|
|
auth_authorise_keyopts(struct ssh *ssh, struct passwd *pw,
|
|
struct sshauthopt *opts, int allow_cert_authority, const char *loc)
|
|
{
|
|
const char *remote_ip = ssh_remote_ipaddr(ssh);
|
|
const char *remote_host = auth_get_canonical_hostname(ssh,
|
|
options.use_dns);
|
|
time_t now = time(NULL);
|
|
char buf[64];
|
|
|
|
/*
|
|
* Check keys/principals file expiry time.
|
|
* NB. validity interval in certificate is handled elsewhere.
|
|
*/
|
|
if (opts->valid_before && now > 0 &&
|
|
opts->valid_before < (uint64_t)now) {
|
|
format_absolute_time(opts->valid_before, buf, sizeof(buf));
|
|
debug("%s: entry expired at %s", loc, buf);
|
|
auth_debug_add("%s: entry expired at %s", loc, buf);
|
|
return -1;
|
|
}
|
|
/* Consistency checks */
|
|
if (opts->cert_principals != NULL && !opts->cert_authority) {
|
|
debug("%s: principals on non-CA key", loc);
|
|
auth_debug_add("%s: principals on non-CA key", loc);
|
|
/* deny access */
|
|
return -1;
|
|
}
|
|
/* cert-authority flag isn't valid in authorized_principals files */
|
|
if (!allow_cert_authority && opts->cert_authority) {
|
|
debug("%s: cert-authority flag invalid here", loc);
|
|
auth_debug_add("%s: cert-authority flag invalid here", loc);
|
|
/* deny access */
|
|
return -1;
|
|
}
|
|
|
|
/* Perform from= checks */
|
|
if (opts->required_from_host_keys != NULL) {
|
|
switch (match_host_and_ip(remote_host, remote_ip,
|
|
opts->required_from_host_keys )) {
|
|
case 1:
|
|
/* Host name matches. */
|
|
break;
|
|
case -1:
|
|
default:
|
|
debug("%s: invalid from criteria", loc);
|
|
auth_debug_add("%s: invalid from criteria", loc);
|
|
/* FALLTHROUGH */
|
|
case 0:
|
|
logit("%s: Authentication tried for %.100s with "
|
|
"correct key but not from a permitted "
|
|
"host (host=%.200s, ip=%.200s, required=%.200s).",
|
|
loc, pw->pw_name, remote_host, remote_ip,
|
|
opts->required_from_host_keys);
|
|
auth_debug_add("%s: Your host '%.200s' is not "
|
|
"permitted to use this key for login.",
|
|
loc, remote_host);
|
|
/* deny access */
|
|
return -1;
|
|
}
|
|
}
|
|
/* Check source-address restriction from certificate */
|
|
if (opts->required_from_host_cert != NULL) {
|
|
switch (addr_match_cidr_list(remote_ip,
|
|
opts->required_from_host_cert)) {
|
|
case 1:
|
|
/* accepted */
|
|
break;
|
|
case -1:
|
|
default:
|
|
/* invalid */
|
|
error("%s: Certificate source-address invalid", loc);
|
|
/* FALLTHROUGH */
|
|
case 0:
|
|
logit("%s: Authentication tried for %.100s with valid "
|
|
"certificate but not from a permitted source "
|
|
"address (%.200s).", loc, pw->pw_name, remote_ip);
|
|
auth_debug_add("%s: Your address '%.200s' is not "
|
|
"permitted to use this certificate for login.",
|
|
loc, remote_ip);
|
|
return -1;
|
|
}
|
|
}
|
|
/*
|
|
*
|
|
* XXX this is spammy. We should report remotely only for keys
|
|
* that are successful in actual auth attempts, and not PK_OK
|
|
* tests.
|
|
*/
|
|
auth_log_authopts(loc, opts, 1);
|
|
|
|
return 0;
|
|
}
|